Researchers test various modified lipopolysaccharide structure (LPS) of the Salmonella strain to see how they performed in test tube studies with human cancer cells and in tumour-bearing mice.
The investigational therapy has been found effective in test tube studies with human cancer cells and in tumor-bearing mice. Once it gets to human trials, the therapy would probably be used in conjunction with chemotherapy and radiation therapy, said Dr. Roy Curtiss, professor at Arizona State University and one of the researchers.
"There has long been interest in using genetically engineered microbes to target and destroy cells within solid tumors. I think this study goes a significant way in developing some strategies that will help in the overall means of using Salmonella as part of a cancer therapy," Curtiss noted.
In the new study, researchers focused on modifying the LPSof the Salmonella strain to make the bug less toxic. LPS, found in the outer membrane of bacteria, is one of the major inducers of sepsis, a life-threatening infection. The researchers used genetic engineering to delete genes involved in the synthesis of the LPS.
They identified a particular mutant strain that was the most effective at killing cancer cells and shrinking tumors, and also unable to cause disease. However, this mutant strain was less able to colonize the tumors, although being most effective in killing tumor cells when getting there.
To address this problem, the researchers then added another genetic modification that allowed the Salmonella to be injected in the mouse in a form that would not harm normal, healthy cells, was effective at colonizing tumors and, after entering cancer cells, would turn toxic.
The study was published in the journal mBio